Performance monitoring in Firebase - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Firebase Performance Trace Start and Stop Output

What will be the output in the Firebase console after running this code snippet to start and stop a custom performance trace?

Firebase

const trace = performance.trace('custom_trace');
trace.start();
// some operations
trace.stop();

A No trace appears because start() and stop() methods are asynchronous and need await.

B An error is thrown because 'performance.trace' is not a valid method.

C The trace appears but with zero duration because stop() was called immediately after start().

D A new custom trace named 'custom_trace' appears in the Firebase Performance dashboard with duration matching the operation time.

💡 Hint

Remember that Firebase Performance traces record duration between start and stop calls.

Starting and stopping a custom trace correctly records the time between calls and shows it in the Firebase console under custom traces.

🧠 Conceptual

intermediate

Understanding Firebase Performance Monitoring Data Collection

Which statement correctly describes how Firebase Performance Monitoring collects data from your app?

A It only collects data when the app is running in debug mode.

B It requires manual instrumentation for all traces and network requests to appear in the dashboard.

C It automatically collects traces and network requests without any code changes after SDK initialization.

D It collects data only if the user explicitly grants permission each time the app starts.

💡 Hint

Think about what Firebase SDK does after you add it to your app.

Firebase Performance Monitoring automatically collects common traces and network requests once the SDK is initialized, without needing manual code changes.

❓ Troubleshoot

advanced

Diagnosing Missing Firebase Performance Data

You notice no performance traces appear in the Firebase console after deploying your app with the Performance Monitoring SDK. What is the most likely cause?

A The app is running on a device with network connectivity disabled, preventing data upload.

B The Firebase project is missing the Performance Monitoring API key.

C The SDK requires manual calls to upload data which were not added.

D Performance Monitoring only works on Android devices, not iOS.

💡 Hint

Consider what conditions are needed for data to appear in the console.

If the device has no network connection, performance data cannot be sent to Firebase servers, so no traces appear in the console.

🔀 Workflow

advanced

Configuring Custom Attributes in Firebase Performance Traces

Which sequence correctly describes how to add a custom attribute to a Firebase Performance trace in your app code?

A 1,2,3,4

B 1,3,2,4

C 3,1,2,4

D 2,1,3,4

💡 Hint

Attributes must be set after creating the trace but before stopping it.

You create the trace, add attributes, then start and stop it to record the trace with custom data.

✅ Best Practice

expert

Optimizing Firebase Performance Monitoring for Production

Which practice is best to minimize performance monitoring overhead in a production Firebase app?

A Use the default SDK settings without any configuration changes.

B Disable automatic network request collection and manually instrument only critical requests.

C Disable all custom traces to reduce SDK initialization time.

D Enable verbose logging in production to capture detailed performance data.

💡 Hint

Think about balancing data collection detail with app performance.

Disabling automatic network collection and manually instrumenting critical requests reduces overhead and focuses monitoring on important parts.